Translation of a translation

I'm reading Žert, translated as The Joke in English, in Czech and also comparing it to the Portuguese e-book version I have. Among the many incongruences between the original Czech version and the Portuguese translation, something that really caught my attention was the following passage:

"Položil jsem aktovku na stůl a otevřel okno..."
My free translation in English: I placed my briefcase on the table and opened the window.

The Portuguese version says:
Pus a toalha sobre a mesa e abri a janela. Literally: I placed the towel/tablecloth on the table and opened the table.

Where did a towel/tablecloth come from? I had no idea at first but then I was suddenly struck as if by a thunderbolt. The Portuguese version had been translated from French (a language Milan Kundera often uses to write his books) and not from Czech. Czech aktovka, briefcase, becomes French serviette, which means both a briefcase and a tablecloth. When the Portuguese translator saw that serviette, the most obvious thing to him was that the character was setting the table for a meal, most likely, and then he used the Portuguese word toalha, which means towel or tablecloth!